Single-pipeline pressure-regulating double-end plugging fracturing device and fracturing method

Abstract

The present invention relates to a single-pipeline pressure-regulating double-end plugging fracturing device and a fracturing method, a tail sealer, a connecting pipe and a front sealer are sequentially connected along the drilling direction, a fracturing unit is arranged between the front sealer and the tail sealer, the fracturing unit is composed of a pressure regulating part and a fracturing part, before the ore layer fracturing is performed, the opening pressure of the fracturing part is set by the pressure regulating part, the tail sealer is connected to the high-pressure water injection drill pipe, the high-pressure water injection drill pipe is connected to the pump station, the high-pressure water injection drill pipe is extended into the borehole, so that the fracturing unit is placed at a position where fracturing is required, the tail sealer and the front sealer expand and are tightened on the borehole wall as the water injection pressure increases, and the water injection pressure continues to increase until the opening pressure is reached, at which time the tail sealer, the pressure regulating part and the fracturing part are connected, and high-pressure water enters the fracturing part to realize fixed-point fracturing. The present invention has the advantages of changing the traditional double-pipeline fracturing method, only one pump station is required for one-time pressurization operation, so that the hydraulic fracturing operation is simpler, and the fracturing cost can be greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of fracturing devices, and in particular, relates to a single-pipeline pressure-adjustable double-end plugging fracturing device and a fracturing method. Background Art

[0002] Hydraulic fracturing permeability enhancement technology is to inject high-pressure fluid into the target coal seam, causing the coal reservoir elastic energy to gather and lose control, thereby changing its effective pressure system and effective migration system, prompting the coal reservoir to form a new fracture system or restart and communicate the coal seam self-generated fracture system, forming a new, large-scale connected gas extraction diversion channel, and achieving the purpose of coal seam permeability enhancement. At present, the hydraulic fracturing devices used in domestic hydraulic fracturing permeability enhancement are all dual-pipeline designs, requiring two pump stations to provide water pressure. One pump station enables the hydraulic fracturing device to seal the hole through a separate set of delivery pipelines, and the other pump station is used for fracturing through another separate set of delivery pipelines. It can be seen from this that the processing difficulty is high, it is easy to leak, and the operation is complicated and the construction cost is high. Therefore, the present invention provides a single-pipeline adjustable pressure double-end plugging fracturing device and fracturing method that changes the traditional dual-pipeline fracturing method, only requires one pump station and one pressurization operation, so that the hydraulic fracturing operation is simpler, and the fracturing cost can be greatly reduced. Summary of the invention

[0003] In view of the shortcomings of current dual-pipeline fracturing devices, such as complex operation, high cost, high processing difficulty and easy leakage, the present invention provides a single-pipeline pressure-regulating double-end plugging fracturing device and a fracturing method, which only requires one pump station and one pressurization operation, making hydraulic fracturing operation simpler and significantly reducing fracturing costs.

[0004] The specific technical solutions of the present invention are as follows:

[0005] A single-pipeline pressure-regulating double-end plugging fracturing device, the fracturing device comprises a tail hole sealer, a front hole sealer and a fracturing unit, one end of the tail hole sealer is connected to a high-pressure water injection drill pipe through a water inlet joint, and the other end is connected to the front hole sealer through a connecting pipe, and the front hole sealer and the tail hole sealer are both elastic capsules; the fracturing unit is arranged between the front hole sealer and the tail hole sealer, and the fracturing unit consists of a pressure regulating part and a fracturing part, the pressure regulating part is provided with a pressure limiting opening device located between the tail hole sealer and the fracturing part, one end of the pressure regulating part is connected to the tail hole sealer, and the other end is connected to the fracturing part through the pressure limiting opening device, and the fracturing part is arranged between the front hole sealer and the pressure regulating part.

[0006] Furthermore, the pressure-limiting opening device includes a valve body, which is located between the tail hole sealer and the fracturing part. A first through hole connected to the tail hole sealer and a second through hole connected to the fracturing part are provided inside the valve body. The axis of the first through hole coincides with the axis of the second through hole, and the aperture of the first through hole is smaller than the aperture of the second through hole. A sealing member capable of sealing the first through hole and a spring for connecting the sealing member are arranged in the second through hole. The spring is arranged between the sealing member and the fracturing part. An adjusting member is movably connected to the valve body. The adjusting member can move along the axis of the spring under the drive of an external force and press against an end of the spring away from the sealing member.

[0007] Furthermore, the blocking member is a spherical body or a semi-spherical body.

[0008] Furthermore, a groove matching the arc surface of the blocking member is provided at the connection between the first through hole and the second through hole.

[0009] Furthermore, the adjusting part includes an adjusting nut and a locking nut threadedly connected to the outer surface of the valve body, the adjusting nut has a top sleeve that is turned inward from the end of the valve body away from the tail hole sealer and inserted into the second through hole, one end of the spring is connected to the sealing part, and the other end is connected to the top sleeve, and the locking nut is connected to the end of the adjusting nut away from the top sleeve.

[0010] Furthermore, the fracturing part is provided with a fracturing pipe, a sealing end of the fracturing pipe is fixedly connected to the front hole sealer, and the other end is communicated with the second through hole of the valve body, and a plurality of groups of fracturing holes are arranged on the fracturing pipe at intervals along the axial direction of the fracturing pipe, and each group of fracturing holes includes a plurality of fracturing holes evenly opened along the circumference of the pressure pipe.

[0011] Furthermore, the elastic bladder is made of rubber and steel wire braid.

[0012] Furthermore, there are at least two connecting pipes, and the connecting pipes are evenly arranged along the circumference of the fracturing unit. A tip is provided at one end of the front sealer away from the rear sealer.

[0013] A fracturing method using a single-pipeline pressure-regulating double-end plugging fracturing device comprises the following steps:

[0014] S1. Adjust the adjusting nut to set the opening pressure of the fracturing unit. After setting, rotate the locking nut to lock the adjusting nut.

[0015] S2, connect the tail hole sealer to the water outlet end of the high-pressure water injection drill pipe;

[0016] S3, extending the plugging fracturing device into the borehole through the high-pressure water injection drill pipe, and placing the fracturing unit at the position where the rock formation needs to be fractured;

[0017] S4, supplying high-pressure water to the high-pressure water injection drill pipe through a pump station connected to the high-pressure water injection drill pipe, and the high-pressure water enters the tail hole sealer, the connecting pipe and the front hole sealer in sequence through the high-pressure water injection drill pipe until the tail hole sealer and the front hole sealer are full, and gradually increasing the supply pressure of the pump station, so that the outer walls of the tail hole sealer and the front hole sealer expand and are tightened on the hole wall of the borehole, thereby sealing the hole wall of the borehole, and at this time, the water pressure does not connect the pressure regulating part with the fracturing part;

[0018] S5. Continue to increase the supply pressure of the pump station until the opening pressure of the fracturing unit is reached. At this time, the high-pressure water injection drill pipe, the pressure regulating part and the fracturing part are connected, and high-pressure water enters the fracturing part to realize drilling fracturing.

[0019] Beneficial effect: the tail hole sealer is connected with the front hole sealer through a connecting pipe, the tail hole sealer is connected with the high-pressure water injection drill pipe, and a fracturing unit is arranged between the tail hole sealer and the front hole sealer, the fracturing unit is connected with the tail hole sealer, and the fracturing unit comprises a pressure regulating part arranged near the end of the tail hole sealer and a fracturing part arranged between the pressure regulating part and the front hole sealer; the pressure regulating part divides the high-pressure water into two pressure ranges, namely the sealing pressure and the fracturing pressure, when the high-pressure water is injected into the tail hole sealer, the high-pressure water in the tail hole sealer enters the front hole sealer through the connecting pipe, and the pressure of the tail hole sealer is equal to that of the front hole sealer, and the pressure of the tail hole sealer and the front hole sealer is gradually increased by gradually pressurizing the high-pressure water injection drill pipe, until the outer walls of the front hole sealer and the tail hole sealer are in contact with the wall of the borehole, thereby achieving the purpose of The borehole wall is sealed. Within this pressure range, the pressure regulating part is not connected with the fracturing part, and high-pressure water cannot enter the fracturing part. The pressure within this range becomes the sealing pressure, and the high-pressure water in this range is called sealing water. After that, the water pressure circulating in the high-pressure water injection drill pipe is continuously increased until the pressure regulating part of the fracturing unit is connected with the fracturing part, that is, the preset opening pressure is reached. The high-pressure water is fractured through the fracturing part and enters the cracks of the borehole. The tail sealer and the front sealer are always in a tensioned state with the borehole wall within this pressure range. This pressure range is the fracturing pressure, and the high-pressure water in this range is called fracturing water. According to the actual situation of the borehole, the pressure regulating part is adjusted to set the opening pressure of the pressure regulating part, that is, the minimum value of the fracturing pressure, so that the pressure regulating part is connected with the fracturing part, and the water of the present invention is transported to the part of the borehole required for fracturing through the high-pressure water injection drill pipe. The present invention adopts the above-mentioned structure, and sets the fracturing unit as a pressure regulating part and a fracturing part. Different opening pressures of the fracturing part are set by the pressure regulating part according to different needs to adapt to the complex changes on site. The dual-pipeline fracturing system is simplified to a single pipeline, and the opening pressure of the pressure regulating part is adjustable and controllable. Only one pump station and one pressurization operation are required, which makes the hydraulic fracturing operation simpler and can greatly reduce the fracturing cost. In addition, the above-mentioned device of the present invention can realize multiple features such as rapid plugging and cyclic fracturing, which not only solves the problem of difficult collapse of the hard and thick roof around the mining area and in the tunnel, but also greatly reduces the installation operation intensity and plugging time, meets the requirements of short underground operation time, high efficiency and low cost, and provides technical guidance and equipment support for the treatment of hard and thick roof in coal mines. A double-end plugging setting is adopted, and the fracturing unit can be sent to a designated position according to the pre-setting to realize fixed-point fracturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the structure of a fracturing device;

[0021] Figure 2 Schematic diagram of the structure of the fracturing unit.

[0022] In the figure: 1, water inlet joint, 2, tail hole sealer, 3, fracturing unit, 4, front hole sealer, 5, top, 6, connecting pipe, 7, first through hole, 8, plugging piece, 9, adjusting nut, 10, fracturing pipe, 11, fracturing hole, 12, top sleeve, 13, locking nut, 14, spring. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0024] A single-pipeline pressure-adjustable double-end plugging fracturing device, such as Figure 1 As shown, it includes a tail sealer 2, a connecting pipe 6 and a front sealer 4 which are sequentially connected along the extension direction of the borehole, and a fracturing unit 3 is arranged between the front sealer 4 and the tail sealer 2. In order to make the tail sealer 2 fully connected with the front sealer 4, and to avoid uneven high-pressure water entering the front sealer from the tail sealer 2, or excessive local pressure on a single connecting pipe 6, which causes uneven expansion of the front sealer, at least two connecting pipes 6 are provided, and the connecting pipes 6 are evenly arranged along the circumference of the fracturing unit 3. Among them, a water inlet joint 1 is constructed at one end of the tail sealer 2 away from the front sealer, and the water outlet end of the high-pressure water injection drill pipe is connected to the water inlet joint 1 to achieve connection with the tail sealer 2, and the water inlet end of the high-pressure water injection drill pipe is connected to a pump station. In order to facilitate production and manufacturing, the tail hole sealer and the front hole sealer are effectively elastically expanded under the action of high-pressure water, so that the outer walls of the tail hole sealer and the front hole sealer are tensioned on the hole wall of the drilled hole. The tail hole sealer is a first capsule made of rubber and steel wire braid, and the front hole sealer is a second capsule made of rubber and steel wire braid.

[0025] like Figure 2 As shown, the fracturing unit 3 has a pressure regulating part arranged near the end of the tail sealer 2 and a fracturing part arranged between the pressure regulating part and the front sealer 4. The purpose of setting the pressure regulating part in the fracturing unit 3 is to divide the high-pressure water passing through the high-pressure water injection drill pipe into two pressure ranges. When the pressure range of the high-pressure water is such that the outer walls of the tail sealer 2 and the front sealer 4 are respectively stretched on the borehole wall of the borehole, and the pressure regulating part is not connected with the fracturing part within this pressure range, the high-pressure water cannot enter the fracturing part for fracturing. This pressure range is called the sealing pressure, and the high-pressure water within this range is called sealing water. The minimum pressure of the other pressure range is greater than the maximum value of the sealing pressure. When the pressure range of the high-pressure water reaches such that the tail sealer 2, the pressure regulating part and the fracturing part are connected, the high-pressure water enters the fracturing part for fracturing, and the tail sealer 2 and the front sealer 4 are always in a state of tension with the borehole wall within this pressure range. This pressure range is called the fracturing pressure, and the high-pressure water within this range is called fracturing water.

[0026] In order to effectively control the minimum value of the fracturing pressure, so that the fracturing water through the fracturing unit can achieve the expected fracturing effect on the ore layer, such as Figure 2 As shown, the pressure regulating part is provided with a valve body between the tail hole sealer 2 and the fracturing part, and a first through hole 7 connected to the tail hole sealer 2 and a second through hole connected to the fracturing part are respectively opened in the valve body, the axis of the first through hole 7 coincides with the axis of the second through hole, and the aperture of the first through hole 7 is smaller than the aperture of the second through hole, a plugging member 8 capable of plugging the first through hole 7 is installed in the second through hole, and a spring 14 is installed in the second through hole, the spring 14 is arranged between the plugging member and the fracturing part, and an adjusting member that can move along the axis of the spring 14 under the drive of an external force is movably connected to the valve body, and the adjusting member presses against the adjusting member at one end of the spring 14 away from the plugging member. Among them, in order to improve the ability of the plugging member to fully seal the first through hole 7 under the pressure of the spring 14, the implementation method adopted is: the plugging member 8 is a sphere or a hemisphere, and the sphere can be a steel ball, and a circular arc groove matching the circular arc surface of the plugging member is formed at the connection between the first through hole 7 and the second through hole. The adjusting member includes an adjusting nut 9 threadedly connected to the outer surface of the valve body, and the adjusting nut 9 has a top sleeve 12 turned inward from the end of the valve body away from the tail hole sealer into the second through hole, wherein, when the adjusting nut 9 is rotated, the top sleeve 12 moves along the axis of the second through hole with the adjusting nut 9, thus constituting different compression degrees of the top sleeve on the spring 14, thereby adjusting the pressure of the high-pressure water to push the sealing member away from the arc-shaped groove. In order to prevent the adjusting nut 9 from relative displacement with the valve body after the adjustment is completed, a locking nut 13 is threadedly connected to the valve body, and ensure that the locking nut 13 is connected to the end of the adjusting nut 9 away from the fracturing part to achieve locking of the adjusting nut 9.

[0027] The fracturing part includes a fracturing pipe 10, the plugging end of the fracturing pipe 10 is fixedly connected to the end of the corresponding front plugger 4, and the other end of the fracturing pipe 10 is connected to the second through hole of the valve body. A plurality of groups of fracturing holes 11 are spaced apart along the axial direction of the fracturing pipe 10 on the fracturing pipe 10, and each group of fracturing holes 11 includes a plurality of fracturing holes 11 uniformly opened along the circumference of the fracturing pipe 10, so that high-pressure fracturing water can fully penetrate into the corresponding mineral layer cracks from each fracturing hole 11.

[0028] In order to allow the front hole sealer 4 to smoothly enter the borehole along with the high-pressure water injection drill pipe and avoid the drilling causing obstruction to the front hole sealer 4, a tip 5 is formed at one end of the front hole sealer 4 away from the rear hole sealer 2.

[0029] The specific operation steps of using the above-mentioned single-line adjustable pressure double-end plugging fracturing device to increase the drilling pressure are as follows:

[0030] S1. Adjust the adjusting nut 9 to set the opening pressure of the fracturing unit 3. After setting, rotate the locking nut 13 to lock the adjusting nut 9 with the locking nut 13;

[0031] S2, connect and fix the tail hole sealer 2 to the water outlet end of the high-pressure water injection drill pipe;

[0032] S3, extending the high-pressure water injection drill rod into the borehole, and positioning the fracturing unit 3 at the part of the stratum that needs fracturing;

[0033] S4, supplying high-pressure water to the high-pressure water injection drill pipe through a pump station connected to the high-pressure water injection drill pipe, and the high-pressure water enters the tail hole sealer 2, the connecting pipe 6 and the front hole sealer 4 in sequence through the high-pressure water injection drill pipe until the tail hole sealer 2 and the front hole sealer 4 are full, increasing the supply pressure of the pump station, so that the outer walls of the tail hole sealer 2 and the front hole sealer 4 are expanded and tightened on the hole wall of the borehole, and at this time, the water pressure does not connect the pressure regulating part with the fracturing part;

[0034] S5. Continue to increase the supply pressure of the pump station until the opening pressure of the fracturing unit 3 is reached, that is, the high-pressure water injection drill pipe, the pressure regulating part and the fracturing part are connected, and the high-pressure water enters the fracturing part and fractures the borehole through the fracturing part.

[0035] After high-pressure water is injected into the tail hole sealer 2, the high-pressure water in the tail hole sealer 2 enters the front hole sealer 4 through the connecting pipe 6, and the pressure of the tail hole sealer 2 is equal to that of the front hole sealer 4. By gradually pressurizing the high-pressure water injection drill pipe, the pressure of the tail hole sealer 2 and the front hole sealer 4 gradually increases until the outer walls of the front hole sealer 4 and the tail hole sealer 2 are in contact with the wall of the borehole, thereby achieving the plugging of the borehole wall. This range of high-pressure water is called sealing water; after that, the flow rate is continuously increased. The water pressure of the high-pressure water injection drill pipe is increased until the pressure regulating part of the fracturing unit 3 is connected to the fracturing part, that is, the preset fracturing pressure. The high-pressure water is fractured through the fracturing part and enters the cracks of the borehole. The high-pressure water in this range is called fracturing water. According to the actual situation of the borehole, the pressure regulating part is adjusted to set the opening pressure of the pressure regulating part, that is, the fracturing pressure, so that the pressure regulating part is connected to the fracturing part, and the pressure regulating part is transported to the part of the borehole required for fracturing through the high-pressure water injection drill pipe to perform fixed-point fracturing.

[0036] Therefore, the present invention has the characteristics of changing the traditional dual-pipeline fracturing method, requiring only one pump station and one pressurization operation, making the hydraulic fracturing operation simpler and significantly reducing the fracturing cost.

[0037] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A single-pipeline pressure-regulating double-end plugging fracturing device, characterized in that: The fracturing device comprises a tail hole sealer, a front hole sealer and a fracturing unit. One end of the tail hole sealer is connected to the high-pressure water injection drill pipe through a water inlet joint, and the other end is connected to the front hole sealer through a connecting pipe. Both the front hole sealer and the tail hole sealer are elastic capsules. The fracturing unit is arranged between the front hole sealer and the tail hole sealer. The fracturing unit consists of a pressure regulating part and a fracturing part. The pressure regulating part is provided with a pressure limiting opening device located between the tail hole sealer and the fracturing part. One end of the pressure regulating part is connected to the tail hole sealer, and the other end is connected to the fracturing part through the pressure limiting opening device. The fracturing part is arranged between the front hole sealer and the pressure regulating part. The pressure-limited opening device comprises a valve body, the valve body is located between the tail hole sealer and the fracturing part, a first through hole communicating with the tail hole sealer and a second through hole communicating with the fracturing part are arranged inside the valve body, the axes of the first through hole and the second through hole coincide, and the aperture of the first through hole is smaller than that of the second through hole, a plugging member capable of plugging the first through hole and a spring for abutting the plugging member are arranged in the second through hole, the spring is arranged between the plugging member and the fracturing part, an adjusting member is movably connected to the valve body, the adjusting member can move along the axis of the spring under the driving of an external force and press against an end of the spring away from the plugging member; The elastic capsule is made of rubber and steel wire braid; There are at least two connecting pipes, and the connecting pipes are evenly arranged along the circumference of the fracturing unit. A tip is provided at one end of the front sealer away from the rear sealer.

2. A single-pipeline pressure-regulating double-end plugging fracturing device according to claim 1, characterized in that: The blocking member is a spherical body or a semi-spherical body.

3. A single-pipeline pressure-regulating double-end plugging fracturing device according to claim 2, characterized in that: A groove matching the arc surface of the blocking member is provided at the connection between the first through hole and the second through hole.

4. A single-pipeline pressure-regulating double-end plugging fracturing device according to claim 2, characterized in that: The adjusting part includes an adjusting nut and a locking nut threadedly connected to the outer surface of the valve body, the adjusting nut has a top sleeve which is turned inward from the end of the valve body away from the tail hole sealer and is inserted into the second through hole, one end of the spring is in contact with the sealing part, and the other end is in contact with the top sleeve, and the locking nut is in contact with the end of the adjusting nut away from the top sleeve.

5. The single-pipeline pressure regulating double-end plugging fracturing device according to claim 2, characterized in that: The fracturing part is provided with a fracturing pipe, a sealing end of the fracturing pipe is fixedly connected to the front hole sealer, and the other end is communicated with the second through hole of the valve body. A plurality of groups of fracturing holes are arranged on the fracturing pipe at intervals along the axial direction of the fracturing pipe, and each group of fracturing holes includes a plurality of fracturing holes evenly opened along the circumference of the fracturing pipe.

6. A fracturing method using the single-pipeline pressure regulating double-end plugging fracturing device according to any one of claims 1 to 5, characterized in that: The steps include: S1. Adjust the pressure regulating part to set the opening pressure of the fracturing part; S2, connect the tail hole sealer to the water outlet end of the high-pressure water injection drill pipe; S3, extending the plugging fracturing device into the borehole through the high-pressure water injection drill pipe, and placing the fracturing unit at the position where the rock formation needs to be fractured; S4, supplying high-pressure water to the high-pressure water injection drill pipe through a pump station connected to the high-pressure water injection drill pipe, and the high-pressure water enters the tail hole sealer, the connecting pipe and the front hole sealer in sequence through the high-pressure water injection drill pipe until the tail hole sealer and the front hole sealer are full, and gradually increasing the supply pressure of the pump station, so that the outer walls of the tail hole sealer and the front hole sealer expand and are tightened on the hole wall of the borehole, thereby sealing the hole wall of the borehole, and at this time, the water pressure does not connect the pressure regulating part with the fracturing part; S5. Continue to increase the supply pressure of the pump station until the opening pressure of the fracturing unit is reached. At this time, the high-pressure water injection drill pipe, the pressure regulating part and the fracturing part are connected, and high-pressure water enters the fracturing part to realize drilling fracturing.

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